a) Field of the Invention
This invention relates to a one-way clutch which is employed as a component for transmitting a torque, preventing reverse rotation or like purposes in a drive mechanism of an automotive vehicle or the like.
b) Description of the Related Art
One-way clutches are widely used as automobile components. In a one-way clutch, an inner ring and an outer ring repeatedly undergo relative sliding motion due to engagement between and idling of the inner and outer rings. Substantial heat generation and friction therefore occur unless sufficient lubrication is applied. Further, it is also necessary to feed a lube oil sufficiently to the one-way clutch to avoid irregular rotation and/or seizure of one or more end bearings employed in the one-way clutch.
The construction of a conventional one-way clutch will first be described with reference to FIG. 2, which illustrates an inner ring 10, an outer ring 20, a one-way clutch 30, end bearings 40 arranged on opposite sides of the one-way clutch, a stop ring 60 for holding the one-way clutch in place, a spacer 75 for regulating the position of the one-way clutch 30 in an axial direction, and a central axis 90 of rotation of the entire mechanism.
A lube oil delivered from a lube oil pump (not shown) is caused to flow and scatter to the periphery of the one-way clutch 30 as indicated by arrow S.
In a conventional one-way clutch of the above-described type, introduction of a lube oil into the one-way clutch is not expected to achieve substantial distribution of the lube oil within the one-way clutch where an inner ring is fixed, although the lube oil is surely and fully distributed inside the one-way clutch under centrifugal lubricating action where the inner ring rotates. Unless the inner ring rotates, it is therefore necessary to increase the capacity of a lube oil pump as a supply source for the lube oil. An increase in the supply of the lube oil, however, leads to greater agitation resistance and viscous resistance due to the lube oil remaining in a larger amount around the one-way clutch, resulting in a greater power loss.
With a view toward feeding the lube oil, which has scattered to the periphery of the one-way clutch, into the one-way clutch to assure supply of the lube oil in a sufficient amount to the interior of the one-way clutch, it has accordingly been proposed to provide an inner circumferential wall of each end bearing with a helical oil groove so that, under relative rotation between the end bearing and the inner or outer ring, pumping action is developed to guide the lube oil, which has scattered to the periphery of the one-way clutch, to the interior of the one-way clutch.
FIG. 1A is a front view of such an end bearing 40. It is to be noted that only the left-hand half of the end bearing 40 is shown in FIG. 1A. FIG. 1B is a side view of the end bearing 40 as viewed in the direction of arrow IB in FIG. 1A. These drawings shown an example in which an inner circumferential wall 121 is provided with a helical oil groove 123. Numeral 124 indicates an opening of the helical oil groove 123, whereas numeral 122 designates an outer peripheral wall of the end bearing 40. Further, FIG. 1C illustrates a modification of the end bearing 40, in which an oil hole 125 is formed to allow the lube oil to flow in to a side of a clutch mechanism.
To allow the helical oil groove 123 to effectively exhibit pumping action, however, the lube oil which has scattered around has to be efficiently collected to or around the inner circumferential wall of the end bearing 40.